AVI ADM woofer power amp rated @ 250W. BS or not?

[oldric_naubhoff]

Oldric, I have just had a look at the websites of ATC, PMC, Barefoot, and Quested. All very big hitters in the active speaker world. None of them give any more info about amp power than AVI, none of them give figures into 8ohm. Nor do Mackie, nor do Genelec. AVI are quoting their amps inline with the other manufacturers I've looked at - they are quoting into the nominal impedance of the driver they are attached to. Let me know if you find an active speaker manufacturer who quotes power figures in the way you think they should.

in that case would you agree it's prudent to ask for passive alternatives to AVIs being driven by a 250W amp, or even 325W amp in their price bracket? because every time I see AVIs being recommended everybody is boasting you get a great sounding speakers + DAC + preamp + 250W of amplification in one package for unbeatable price. where in fact the amp included is no better than a Roksan Kandy. now you know where I'm coming from?

 

[fr0g]

So long as it can reproduce the dynamic peaks of music at the desired volume level that's all that matters.

...and as long as you don't push the amp too hard, then you're fine. Applies across the board no matter what. Yes, you can have 200wpc, but you can as easily use a 30-watter with a pair of Mission 752s, say, and it'll work a treat. I have done and it did.

I agree.

I used a 20 wpc Nad for a while at close range and quietly (say 80 dB average), and later, a 15 wpc Bantam t-amp. Both at less than 2 feet, both with budget MS 902 speakers (about 89 on the sensitivity scale), and they sounded pretty good.

Neither would nicely produce high volumes, but were fantastic anyway.

I wouldn't trade in the quality and flexibility insofar as volume that I now have in the same position with my ADMs though

 

[Craig M.]

Oldric, I have just had a look at the websites of ATC, PMC, Barefoot, and Quested. All very big hitters in the active speaker world. None of them give any more info about amp power than AVI, none of them give figures into 8ohm. Nor do Mackie, nor do Genelec. AVI are quoting their amps inline with the other manufacturers I've looked at - they are quoting into the nominal impedance of the driver they are attached to. Let me know if you find an active speaker manufacturer who quotes power figures in the way you think they should.

in that case would you agree it's prudent to ask for passive alternatives to AVIs being driven by a 250W amp, or even 325W amp in their price bracket? because every time I see AVIs being recommended everybody is boasting you get a great sounding speakers + DAC + preamp + 250W of amplification in one package for unbeatable price. where in fact the amp included is no better than a Roksan Kandy. now you know where I'm coming from?

I think what you see as boasting I see as them stating a fact, they DO come with 325 watts of onboard amps. I would say though that you are missing something quite crucial in your attempts to find a common ground between the amps in an active speaker, and an amp for a comparable passive speaker: what the amp is connected to. I'm sure you understand the amps in an active system are connected directly to the drivers - ensuring that all the amps power is going to the driver, whereas a passive has a crossover inbetween them. It won't suprise you that I've read up on the differences between the 2 systems, and all the papers I've read by audio engineers agree that a good rule of thumb is that the passive crossover tends to waste about 50% of an amps power. I think when you take this into account, it is entirely fair to say the ADMs have the 8 ohm equivalent of 325 watts in them.

 

[JMacMan]

Oldric, I have just had a look at the websites of ATC, PMC, Barefoot, and Quested. All very big hitters in the active speaker world. None of them give any more info about amp power than AVI, none of them give figures into 8ohm. Nor do Mackie, nor do Genelec. AVI are quoting their amps inline with the other manufacturers I've looked at - they are quoting into the nominal impedance of the driver they are attached to. Let me know if you find an active speaker manufacturer who quotes power figures in the way you think they should.

in that case would you agree it's prudent to ask for passive alternatives to AVIs being driven by a 250W amp, or even 325W amp in their price bracket? because every time I see AVIs being recommended everybody is boasting you get a great sounding speakers + DAC + preamp + 250W of amplification in one package for unbeatable price. where in fact the amp included is no better than a Roksan Kandy. now you know where I'm coming from?

I think what you see as boasting I see as them stating a fact, they DO come with 325 watts of onboard amps. I would say though that you are missing something quite crucial in your attempts to find a common ground between the amps in an active speaker, and an amp for a comparable passive speaker: what the amp is connected to. I'm sure you understand the amps in an active system are connected directly to the drivers - ensuring that all the amps power is going to the driver, whereas a passive has a crossover inbetween them. It won't suprise you that I've read up on the differences between the 2 systems, and all the papers I've read by audio engineers agree that a good rule of thumb is that the passive crossover tends to waste about 50% of an amps power. I think when you take this into account, it is entirely fair to say the ADMs have the 8 ohm equivalent of 325 watts in them.

I tend to agree Craig; note, I'm not a qualified electronics engineer though.

However, I rather feel that this thread is as much about audiophile semantics and obsessions as it is any effort to ascertain if AVI is fiddling the figures.

It may be of deep, life changing relevance to the obsessive audiophile/home hobbyist, but I would wager that most users of active speakers don't care that much about the specs, and just use the kit and enjoy the music.

When I bought my Merc, a BMW friend and fan tried to argue against my buying a Benz, and buy a BMW instead - quite why I don't know, - as I like the more generally sporty BMW, but prefer the Benz overall being in the situation of being able only to own/run one vehicle. He presented all sorts of facts, figures and anecdotal tales. Another friend tried to convince me to buy a Toyota - much more sensible car, but having driven one, I don't want to live with one, and would resent spending any money on it whatsoever, no matter how cheap it was to run.

Similarly with HiFi, certain folks endeavoured quite strongly to persuade me that even the AVI 9.1's in the latest RSS etc model, would better the B&O's I now have, let alone the ADM40's which are supposedly better than anything, at any price. Never mind that I don't like speakers on stands, and don't want additional boxes in the form of subs to balance out the sound for the sorts of music I tend to favour. Another audiophile friend worked really hard on me to excercise extreme caution with active speakers, re what if things go wrong, can't swap the amps out if they fail etc, etc.

I don't quite know what it is psychologically that causes many hobbyists to try and persuade friends and others to subscribe to their world view with respect to the shared hobby - maybe insecurity, maybe the need to feel a mutually shared and appreciated world viewpoint as an expression and extension of the friendship perhaps.

Either way, it's my experience that when friends and strangers offer advice, (often unasked for) it's usually about what they would do, or choices they would make, NOT what might be best for ME.

So, I would simply say that whilst analysing the bits and pieces of an active speaker will consume and enthrall the home hobbyist/audiophile, the most likely end user, who wants a plug and play, fiddle free music/AV system, for which reasons they chose an active system in the first place, will simply plug it in, and get on with the listening - and importantly - the rest of their life. Their is a lot more to life than fiddling about or worrying about audio IMHO & E.

JMac

 

[Phileas]

every time I see AVIs being recommended everybody is boasting you get a great sounding speakers + DAC + preamp + 250W of amplification

Perhaps a slight exaggeration there?

I think people, who've heard ADMs and sensed the massive headroom available, could be forgiven for taking the power ratings at face value.

(Also, bear in mind that, as far as I understand it, the amps are designed specifically for the requirements of playing music - something which has implications for the kind of power supply required.)

 

[BigH]

On eof the problems with amps for passive speakers is the manufacturer does not know what it will be hooked up to, whether it is 4 ohms or 8ohms, of course the 4ohms can dip down even lower, also they do not know what speaker cable and how long it will be, whether 1m or 10ms? I see NAinm used to state you have to have min. 3.5m of speaker cable for some of their amps. With actives it is 1 amp per driver, they know the load and cable, so that amp is dedicated to just drive that one driver, no crossover filtering the sounds either.

 

[WinterRacer]

What a strange thread, of course the power rating isn't BS.

AVI have described (more than once) how the ADM amps are designed for playing music rather than test tones (audiophiles beware >) )

Average power levels when playing normal music at loud levels are pretty small, but it does require large bursts of power if you don't want to clip on loud sections. ADM amps will produce 250watts rms into the drive units they're connected to, but they won't sustain it for very long, the power supply will sag pretty quickly under these conditions.

If the amps did sustain 250W rms for any significant length of time, the drive units would burn out very quickly and of course, there's no need to when playing music.

Designing amps the way some people here seem to want is very expensive and pointless for real world music listening conditions.

Bottom line, the specs aren't BS and ADMs are loud and sound clean doing it.

 

[altruistic.lemon]

Sad that the standard for RMS - continuous - involves a test tone, and that the standard was invoked to prevent manufacturers making outrageous claims base on peak, short-term power, and that AVI have, judging by the above post, decided to return to that.

Maybe you mean peak, winterracer, and not rms - see here: http://en.wikipedia.org/wiki/Audio_power#Continuous_power

 

[WinterRacer]

Sad that the standard for RMS - continuous - involves a test tone, and that the standard was invoked to prevent manufacturers making outrageous claims base on peak, short-term power, and that AVI have, judging by the above post, decided to return to that.

Maybe you mean peak, winterracer, and not rms - see here: http://en.wikipedia.org/wiki/Audio_power#Continuous_power

Nope, I meant rms, but not for a sustained time. Remember power isn't time related, so an amp can produce 250 watts rms, but some can do it for long periods, others like AVI's (& most AV amps) can only do it for short periods. Real world listening conditions require low average power levels with high peaks (unless the music is horrribly compressed and played VERY loudly).

My view is that the standard has resulted in huge & expensive amps that don't really relate to what they have to do. The specs look impressive, but the are completely over engineerd for what the actually need to do. I agree a standard is needed, just not the one we've got!

 

[oldric_naubhoff]

It won't suprise you that I've read up on the differences between the 2 systems, and all the papers I've read by audio engineers agree that a good rule of thumb is that the passive crossover tends to waste about 50% of an amps power. I think when you take this into account, it is entirely fair to say the ADMs have the 8 ohm equivalent of 325 watts in them.

I'm so disappointed Craig. I was expecting more from you. and what is this supposed to mean? specs should represent equivalents now? sounds like a good marketing talk. maybe AVI should put it on their website. but don't forget about your copyrights.

maybe you shouldn't read too much tech articles too. it seems you don't fully grasp the meaning if you're now referring to "equivalents". and such literature might squash your creativity too

 

[oldric_naubhoff]

I think people, who've heard ADMs and sensed the massive headroom available, could be forgiven for taking the power ratings at face value.

certainly, since mere 10W in room makes speakers sound very loud

(Also, bear in mind that, as far as I understand it, the amps are designed specifically for the requirements of playing music - something which has implications for the kind of power supply required.)

from your talk it would seem that stuffing in any substandard power supply will do if you can convince customers that this is the way to go.

 

[oldric_naubhoff]

On eof the problems with amps for passive speakers is the manufacturer does not know what it will be hooked up to, whether it is 4 ohms or 8ohms, of course the 4ohms can dip down even lower, also they do not know what speaker cable and how long it will be, whether 1m or 10ms? I see NAinm used to state you have to have min. 3.5m of speaker cable for some of their amps. With actives it is 1 amp per driver, they know the load and cable, so that amp is dedicated to just drive that one driver, no crossover filtering the sounds either.

sorry man, but you're talk is delusional. what's wrong with an amp stable in any load from 16 Ohm and more down to 1 Ohm? and with that doubling output power with each halving of impedance. what's wrong with an amp with negligible THD IMD at any power level and over entire audio spectrum?

BTW cable length is totally irrelevant in domestic audio use. if you're running kilometers of cables then you have a problem to take it into account. never heard so far of people running kilometers of cables from amp to speakers at home though.

 

[oldric_naubhoff]

AVI have described (more than once) how the ADM amps are designed for playing music rather than test tones (audiophiles beware >) )

actually music consists of "test tones" of different amplitude, frequency and phase.

Average power levels when playing normal music at loud levels are pretty small, but it does require large bursts of power if you don't want to clip on loud sections. ADM amps will produce 250watts rms into the drive units they're connected to, but they won't sustain it for very long, the power supply will sag pretty quickly under these conditions.

If the amps did sustain 250W rms for any significant length of time, the drive units would burn out very quickly and of course, there's no need to when playing music.

in that case you're wrong as it's not an RMS rating. end of story. RMS standard requires delivery of given output power over given period of time at specific distortion level.

there's one more thing you should take into account. class B amps have very poor transient/ burst performance. essentially what they put out into RMS test will not be markedly different into burst test. in which case if AVI amp can't sustain to deliver 250W I can't see how it could deliver it over burst test either.

Designing amps the way some people here seem to want is very expensive and pointless for real world music listening conditions.

looks like designers of micro system known that truth years before AVI found out. although all depends on what you like your music to be presented like. if you want to get a taste of the full orchestra then you'll need powerful amp and more than just tiny monitors on stands.

 

[WinterRacer]

in that case you're wrong as it's not an RMS rating. end of story. RMS standard requires delivery of given output power over given period of time at specific distortion level.

Sorry my dear chap, you need to read up on what rms means as you're getting it confused with continous power.

AVI argue that you need an amp that can produce large peaks for short periods of time. Perhaps you know better than AVI?

 

[Craig M.]

It won't suprise you that I've read up on the differences between the 2 systems, and all the papers I've read by audio engineers agree that a good rule of thumb is that the passive crossover tends to waste about 50% of an amps power. I think when you take this into account, it is entirely fair to say the ADMs have the 8 ohm equivalent of 325 watts in them.

I'm so disappointed Craig. I was expecting more from you. and what is this supposed to mean? specs should represent equivalents now? sounds like a good marketing talk. maybe AVI should put it on their website. but don't forget about your copyrights.

maybe you shouldn't read too much tech articles too. it seems you don't fully grasp the meaning if you're now referring to "equivalents". and such literature might squash your creativity too

I was trying to be polite, but this thread is one of the stupidest I've read in a while. You are the person brought up AVI should quote power into 8ohms so they could be compared to others, you are the person who claimed that because the bass amp has 250 watts into 5 ohms, that means it's the equivalent of 120 watts into 8 ohms (a roksan kandy) - do you remember saying that? I was just pointing out that if that is the way you want to think about it, then you have to consider the crossover, and for the kandy to have the same power going into the speaker driver as the ADM one, it would need to have twice the power - which is around 240 watts. Throw in the tweeter amp and we are upto the kind of power going into the drivers that I mentioned. Remember, you are the one who wanted to compare the amps in the AVIs to something that was measured into 8 ohms. I'm done talking to you now.

 

[Craig M.]

in that case you're wrong as it's not an RMS rating. end of story. RMS standard requires delivery of given output power over given period of time at specific distortion level.

Sorry my dear chap, you need to read up on what rms means as you're getting it confused with continous power.

AVI argue that you need an amp that can produce large peaks for short periods of time. Perhaps you know better than AVI?

Well said WR, that's exactly what I was getting at earlier. For playing music, an amp barely needs any continous power but it does need to be able to produce high wattage peaks for when the music demands it - only well recorded stuff at that. A quick look at the Crown amplifier power calculator tells us that for, as an example, an 89db speaker to play something with no dynamic range at 100db, an amplifier would need about 113 watts. Could you imagine how loud that would be? 100db continous! The National Institute of Occupational Safety and Health recommend only 15 minutes exposure to that sort of noise a day. Now take into account the passive speaker that Crown assume you are using is probably wasting half of that 113 watts, and you are left with an active only needing 52 watts to perform the same feat. And that's playing music, surely the limited range of a 1khz tone will be even easier for the amp?

Then, if we calculate the power needed for an average listening level of 90db (which is the threshold for prolonged exposure to damage hearing), say, with headroom for 15db peaks (which should cover most really dynamic recordings) then we have a requirement for 11 watts continuous with 358 watt peaks. Again, this is for a passive speaker - half those figures for an active.

I have no idea as to the efficiency of the ADMs woofer, so those figures are fairly meaningless, I just used them to emphasise the point about the sort of power amps need to provide for music, and how meaningless continuous power figures are in the context of playing music. Also, AVI are not alone out of active speaker manufacturers in quoting those sort of figures. My Opals, for example, quote continuous, long term, and burst power, with the burst power figure considered the one that relates to playing music.

There is a bit of info in the S.o.S. review of the ADMs about the amps power, and possible listening levels. This is an excerpt from it: "The typical operating SPL (based on 100 hours' continuous operation, using RS426A Program Noise) is rated at 108dB at one metre, per pair of speakers, and this leaves a further 8dB in hand to accommodate instantaneous peaks." That is hellish loud!

 

[oldric_naubhoff]

in that case you're wrong as it's not an RMS rating. end of story. RMS standard requires delivery of given output power over given period of time at specific distortion level.

Sorry my dear chap, you need to read up on what rms means as you're getting it confused with continous power.

seems like you need some reading. RMS is a technique to calculate continuous power.

 

[oldric_naubhoff]

so those figures are fairly meaningless, I just used them to emphasise the point about the sort of power amps need to provide for music, and how meaningless continuous power figures are in the context of playing music.

yeah, but they are pretty much meningfull when assesing quality of the amp's engineering.

 

[WinterRacer]

seems like you need some reading. RMS is a technique to calculate continuous power.

Power is an instaneous measure, it isn't time realated and neither is RMS. Root Mean Square is sine wave max * √ 2.

I think you're asking "Can the AVI ADMs produce 250 watts rms continously for hours on end". I'd rather AVI were allowed to answer for themselves, but my understanding is that no they can't. They're not designed to as it would be a total waste of time and money for all involved.

 

[lindsayt]

Oldric is totally right in everything's he's said in this thread.

The mid-bass amp in the AVI ADM 9's. Is it a 250 watt amp or isn't it? Yes or no?

If I were to dismantle an ADM 9 and use the mid-bass amp with my passive speakers, would my system go as loud and have as much dynamic headroom as my 250 watt amp? If I were to replace the AVI amp in the ADM 9's with my 250 watt amp, would the AVI's have more dynamic headroom and be able to play at a higher maximum volume?

The answer, of course is that ADM 9 amp would not be able to reach the unclipped volumes of my 250 watt amp, neither continuously nor on peaks. The same results would apply whether we used my speakers to test them or the AVI speakers to test them in active mode.

Therefore to me it's a marketing selective truth to describe the AVI amp as a 250 watter.

 

[John Duncan]

Just so's we're clear: I don't actually care.

 

[WinterRacer]

The mid-bass amp in the AVI ADM 9's. Is it a 250 watt amp or isn't it? Yes or no?

Yes.

If I were to dismantle an ADM 9 and use the mid-bass amp with my passive speakers, would my system go as loud and have as much dynamic headroom as my 250 watt amp?

For playing music, rather than a test tone, yes.

If I were to replace the AVI amp in the ADM 9's with my 250 watt amp, would the AVI's have more dynamic headroom and be able to play at a higher maximum volume?

No, but your amp might be able to burn out the drive unit more quickly by playing a test tone very loudly.

 

[oldric_naubhoff]

seems like you need some reading. RMS is a technique to calculate continuous power.

Power is an instaneous measure, it isn't time realated and neither is RMS. Root Mean Square is sine wave max * √ 2.

that below means something completely different:

In the case of a set of

values

, the RMS value is given by this formula:

The corresponding formula for a continuous function (or waveform)

defined over the interval

is

and the RMS for a function over all time is

The RMS over all time of a periodic function is equal to the RMS of one period of the function. The RMS value of a continuous function or signal can be approximated by taking the RMS of a series of equally spaced samples.

 

[lindsayt]

The mid-bass amp in the AVI ADM 9's. Is it a 250 watt amp or isn't it? Yes or no?

Yes.

If I were to dismantle an ADM 9 and use the mid-bass amp with my passive speakers, would my system go as loud and have as much dynamic headroom as my 250 watt amp?

For playing music, rather than a test tone, yes.

I am willing to bet £1450 that your statement is incorrect. And that my 250 watt amp would play a few dbs louder than the AVI amp when playing music, if we avoid clipping in both amps.

If I were to replace the AVI amp in the ADM 9's with my 250 watt amp, would the AVI's have more dynamic headroom and be able to play at a higher maximum volume?

No, but your amp might be able to burn out the drive unit more quickly by playing a test tone very loudly.

You could be right there, but the drive unit is rated at 80 watts for the 100hr RMS noise test, and 150 watts long-term max power. I have a hunch that the AVI amp would not be able to deliver 80 watts RMS for the 100 hr test into this driver without clipping.

For the active ADM 9 test we may have to use 4 Scan-Speak drivers wired in a combination of parallel and series to demonstrate that my 250 watts amps will go louder without clipping.

 

[Alec]

Just so's we're clear: I don't actually care.

They don't care.